This project is designed to develop a device, the digital therapist, that may improve existing assessments of: emotions, processes of psychological change, cognitions and situations affecting behavior in everyday living; this device could also help clients make changes in health-related and other behaviors by teaching them how to "talk to themselves" in a maximally adaptive fashion. During Phase I, 6 prototypes will be constructed. These prototypes will be modified microcassette recorders that will be programmed by therapists using a low-cost microcomputer. Two prototypes will allow for recording by the therapist of 30 10-second messages, which will be played back in random sequence to the user. Message playback is initiated by the user in response to an audio signal from the unit at predetermined intervals throughout the day, but the unit can also be activated at arbitrary times by the user. The remaining 4 prototypes will allow users to record responses to messasges, for later review by the user, therapist, or researcher. A group of clinicians will evaluate the various versions of the digital therapist for ease of use and perceived efficacy. Weight control and hemodialysis clients will participate in a series of multiple-baseline-across-subjects studies designed to test the efficacy of the digital therapist as a means to accelerate changes in refractory behavior patterns (weight loss and compliance with fluid restrictions, respectively). Phast II would include more extensive experimental tests comparing the efficacy of the versions of the digital therapists to extant methods of assessing "consciousness" and psychological change, as well as studying the digital therapist's ability to improve clinical change and facilitate maintenance of such changes. If efficacy and versatility is demonstrated, digital therapists should have considerable appeal to researchers, clinicians, and individuals who attempt to make self-directed changes.